There are a number of patents that disclose intake manifolds having doors that are selectively opened and closed to select the effective lengths of runners from a plenum to individual combustion chambers of an engine. Typically a door is rotatably mounted on the intake manifold and operated by an actuator that is exterior to the plenum. In some manifolds, the door is mounted on a shaft in the manner of a hinge or flap. In others, the shaft is a hollow tube whose wall is selectively apertured so that the doors are thus incorporated into the shaft itself. See U.S. Pat. Nos. 4,643,138; 4,726,329; 4,738,233; 4,854,270 among others for examples of prior manifolds having door-controlled variable length runners.
In general, it is probably not unfair to say that many of the prior manifolds employing doors which are selectively operable to select the effective length of runners from a plenum to engine combustion chambers comprise a substantial number of individual parts that have to be assembled to each other and to the manifold in ways that require a significant number of individual assembly steps. And not all of these steps can be expeditiously performed. Accordingly, there is a need for improvement in such manifolds that makes them more conducive to expeditious fabrication and assembly. It is toward this objective that the present invention is directed.
Briefly, and in a general way, the invention comprises, in one aspect, an intake manifold, and a method of making an intake manifold, wherein a door and a shaft form a unit that is assembled into a manifold by endwise insertion through an opening in an end wall of a plenum, and the plenum is thereafter closed by a closure member that may form a portion of a journal for the shaft.
According to another aspect, the invention comprises the use of an elongated tray to carry the shaft-door unit. The tray, shaft, and door form a sub-assembly that is assembled by insertion lengthwise into the plenum. The tray, in cooperation with clips snapped onto it over the shaft, provides a journal sleeve for the shaft while being suitably slotted to allow the door to swing as the shaft turns in the journal. In the completed manifold, the tray is disposed against the inside wall of the plenum over entrances to the runners and contains a hole pattern shaped for substantial registry with, but slightly larger than, these entrances. The door includes integral perimeter seals for sealing with the margins of these entrances when the door is closed.
According to still another aspect, the invention comprises an elongate journal sleeve that carries the shaft-door unit. The sleeve, shaft, and door form a sub-assembly that is assembled into the plenum. The sleeve has appropriate slotting for the door to pass from its attachment to the shaft through the sleeve's sidewall and to rotate within a limited angular range.
According to yet another aspect, the invention comprises the incorporation of journal sleeve structure into the sidewall of the plenum. The shaft is assembled to the plenum by lengthwise insertion into this journal sleeve structure, and the journal sleeve structure has certain slotting to allow the door to be pre-assembled to the shaft prior to its insertion into the plenum.
Other features, advantages, and benefits of the invention will be seen in the ensuing description and claims which should be considered in conjunction with the accompanying drawings. The drawings disclose a presently preferred embodiment of the invention according to the best mode contemplated at the present time for carrying out the invention.